On Saturday, the ANC's influential women's league pledged its support for Dlamini-Zuma.

"The ANC will elect a new national leadership towards the end of the year," Zuma said.

"Too often, comrades fight for leadership positions as they see leadership as the route to material and personal gain."

As attacks on his presidency grew last year, Zuma survived an attempt by ANC rivals to oust him in November, shrugging off criticism of his conduct by the official anti-graft watchdog and the Constitutional Court.

The watchdog probe uncovered evidence of possible criminal activity in his relationship with the Guptas, a business family accused of wielding undue political influence.

Zuma, who took power in 2009, retains strong loyalty among many rank-and-file ANC party members, as well as its lawmakers.

He struck a humble note at the ANC celebrations in a sports stadium in Soweto, a hotbed of the struggle that ended white-majority rule more than 20 years ago.

"The people have told us that we are too busy fighting each other and we do not pay sufficient attention to their needs," he said.

"The ANC must unite so that we are able to unite the people against our common enemies -- unemployment, poverty and inequality."

Zuma gave a shortened version of his published speech as heavy rain lashed the venue.